Various methods for the enhancement, or intensification, of photographic images are known, which methods often are used for the enhancement of low optical density images. One such method of photographic image enhancement involves the deposition of copper on the silver image of a conventionally developed silver halide-emulsion film, as disclosed, for example, in U.S. Pat. No. 3,674,489 issued July 4, 1972. A basic problem with all such methods of intensification is that large amounts of material must be diffused through the gelatin matrix to increase the size of the grains forming the image. Some of this material frequently deposits at places other than the image and spoils the photograph. In addition, if the photographic image includes dense areas, such areas are completely blocked if sufficient material is deposited for image enhancement of the low optical density areas included thereon.
Autoradiographic photographic image enhancement methods also are known wherein the photographic image is made radioactive in an amount related to the optical density thereof. The radioactive film is placed adjacent a radioactive-sensitive film for exposure thereof to nuclear radiation emitted thereby. Exposure to the radioactive image source continues until the film is properly exposed, after which it is developed. With such nuclear intensification technique, resolution is limited by the resolution of the original negative, the resolution of the autoradiographic film, the evenness of the autoradiographic film contact during exposure, and the range of the radioactive emissions. Since the random direction emissions cannot be conveniently focused, the highest resolution intensification is obtained by contact autoradiography. Additionally, such technique requires specialized equipment and personnel trained in radiochemistry.
With many photographic image enhancement methods the original photographic image is destroyed and can not be readily reconstructed or restored to its original form.